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2. Diagnosis

2.1 Diagnosis

Clinical Questions

How should ADHD be assessed, diagnosed, and monitored, and by whom?

Clinical practice gaps, uncertainties and need for guidance

A consistent, high-quality process for evidence-based diagnostic assessment and monitoring is needed for attention deficit hyperactivity disorder (ADHD) in the Australian context.

Summary of narrative review

Identified sources of guidance on assessment, diagnosis and monitoring included the UK National Institute for Health and Care Excellence (NICE) ADHD guidelines (NICE 2018), which are the highest-rated guidelines for ADHD using the Appraisal of Guidelines for Research & Evaluation (AGREE II) tool (Razzak et al., 2021), National Health and Medical Research Council ADHD practice points (National Health and Medical Research Council, 2012), Royal Australasian College of Physicians ADHD guidance (Royal Australasian College of Physicians, 2009), Canadian ADHD guidelines (Canadian ADHD Resource Alliance 2018), Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) (American Psychiatric Association, 2013) and the International Classification of Diseases (ICD) 11th edition (World Health Organization, 2018).

A recent review of the quality of five major international diagnostic guidelines (National Institute for Health and Care Excellence guidelines, Scottish Intercollegiate Guidelines Network, Canadian Attention Deficit Hyperactivity Disorder Resource Alliance (CADDRA), British Association of Psychopharmacology and the American Academy of Paediatrics) reported that all guidelines recommended a categorical diagnosis approach based on the DSM or ICD classifications (Razzak et al., 2021). All are recommended using interviews and questionnaires, as well as multiple informants, as key components of the diagnostic process.

These five guidelines noted that neuropsychological testing was not required for the diagnosis of ADHD. CAADRA also undertook a review of systematic reviews and meta-analyses published between 2006 and 2016 on the diagnosis of ADHD and found no other strategies that achieved additional benefit beyond that of clinician interview in combination with rating scales. Direct observations such as observing children in their educational setting, neuropsychological and psychoeducational assessments, computerised cognitive assessments, neuroimaging and electroencephalography (EEG) did not increase the accuracy of diagnosis.

Some general guidance is provided below regarding the diagnostic process for ADHD. However, it is noted that psychometric/neuropsychological evaluation (including IQ/cognitive, and educational assessment) could assist with identifying differential and co-occurring conditions when there is diagnostic uncertainty.  For example, it can assist with differentiating between conditions that present with similar symptomology, and for identifying specific language and learning disorders. Psychometric and neuropsychological evaluation can also assist with treatment planning and may help identify and direct which intervention strategies and domains are best to target, given the cognitive strengths and challenges of the person.

Clinical Interview

Clinical interviews are usually carried out by clinicians experienced in the diagnosis of developmental and mental health disorders, such as paediatricians, psychiatrists and psychologists. These may be informal or employ a semi-structured approach for the diagnosis of ADHD. For example, the Diagnostic Interview for ADHD in Adults (DIVA) (Kooij, Franken, & Bron, 2019). The selection of these should be based on awareness of sensitivity and specificity metrics and the experience of the clinician in undertaking such an assessment.

The aim of the interview is to detail the full range of symptoms and signs and their history, including onset, severity and functional impacts, as well as gather information about the person’s strengths and helpful coping strategies. Mental health assessment should include mental health/psychiatric history and assessment for co-occurring psychiatric conditions.

Developmental history, family history, health, social, educational and demographic information, and information about past treatment, should also be gathered. A risk assessment and assessment of current mental state should be conducted as part of the interview. The interview can also highlight if further, more specialist assessments might be necessary to facilitate diagnosis and treatment planning.

A detailed clinical interview may take between 2 and 3 hours and may be arranged over several sessions. For children and adolescents, time is usually set aside to see them separately and also their parents/carers. Other informants may provide additional information and perspectives, such as educators, parents, and partners. This includes requesting access to any prior reports from other health professionals and educational reports (primary, secondary, tertiary) for the clinician to review for identification of symptoms and functional impacts at different developmental stages. This also involves requesting adults provide their educational reports from childhood/adolescence if available.

Standardised Rating Scales

Rating scales can assist with the evaluation of mental health symptoms in adults and the profile of emotional and behavioural symptoms across domains for children and adolescents. They can provide normative data to enable comparisons with the general population and/or specific clinical groups. Broad-band rating scales evaluate behavioural and psychosocial functioning. Narrow-band scales assess for the specific symptoms of ADHD or the presence of other specific conditions, such as depression or anxiety disorders, when these are indicated.

Consideration regarding the selection of rating scales includes understanding inter-rater reliability, validity, sensitivity and specificity levels. It is noteworthy that many scales that assess developmental appropriateness will rely on the rater to judge according to what is considered normal for the child’s age. This may be difficult for non-expert raters and result in errors of interpretation.

Examples of commonly used narrow-band ADHD rating scales are listed in Box 2 below. These are provided for illustrative purposes only, and the sensitivity and specificity of each should be understood for the group and setting under consideration before use. This is not an exhaustive list. For adults, retrospective assessment of childhood/adolescent ADHD symptoms can be conducted by informants completing rating scales used to assess childhood/adolescent symptoms based on their recollections of the person at this age. Some adult rating scales, such as the Wender Utah Rating Scale (Ward, 1993), assess childhood rather than current adulthood symptoms.

Box 2. Example ADHD rating scales to assist in the diagnosis of ADHD

Young children

  • Achenbach System of Empirically Based Assessment – Attention Problems scale
  • Child Behaviour Checklist – DSM Oriented ADHD subscale
  • Brown Attention Deficit Disorder Symptom Assessment Scale (BADDS)


Children and adolescents

  • Vanderbilt ADHD Diagnostic Rating Scale
  • Conners’ 3
  • Swanson, Nolan and Pelham (SNAP) scale
  • ADHD Rating Scale 5
  • Brown Attention Deficit Disorder Symptom Assessment Scale (BADDS)



  • WHO Adult ADHD Self Report Scale (ASRS) (Part A + B)
  • Conners Adult ADHD Rating Scale
  • Wender Utah Rating Scale (WURS)
  • Brown Attention Deficit Disorder Symptom Assessment Scale
  • Barkley Adult ADHD Rating Scale-IV

Educational and occupational functioning

An understanding of the child, adolescent or adult’s performance and adjustment in education settings such as school or university, or an adult’s functioning in the workplace, is an important component of the assessment process. Educators may provide information through broad or narrow band rating scales or via interview, including detail on social and academic functioning, or information can be gathered through reviewing school reports. Observation in educational settings may also be performed by the clinician in the classroom or in less structured situations such as the school playground.

Medical assessment

A medical assessment is an important part of the assessment. Medical assessment can exclude undiagnosed disorders with symptoms that, in rare instances, may mimic or cause some aspects of ADHD, for example, hearing impairment or epilepsy. Medical assessment can also assess for co-occurring developmental, physical, neurological and genetic conditions that may have increased risk of ADHD. This includes the possible contribution of prenatal and perinatal factors known to increase the risk of development of ADHD. Health problems that can exacerbate ADHD, such as sleep deprivation and nutritional deficiencies, also need to be considered as part of the medical assessment.

Other assessment for co-occurring conditions

Psychometric or neuropsychological assessment can be undertaken if there are suspected learning disorders suggested by poor reading, writing or mathematics skills. These can also be undertaken if there is suspected intellectual disability, other cognitive or memory difficulties, or dementia. Similarly, speech and language assessment should be undertaken if indicated.

See Principles and assumptions for guidance on who should diagnose ADHD.
See section 5.3 for guidance on monitoring care for those with ADHD.


Clinical considerations for implementation of the recommendations

Current barriers to diagnostic and treatment services for people with ADHD in Australia include insufficient ADHD-specific clinician expertise and limited public, or low-cost diagnostic services with resources to diagnose ADHD, particularly for those with low socio-economic status and those in regional, rural and remote areas of Australia. Implementation of these recommendations may be impacted by time and funding constraints that may prevent clinicians from conducting thorough diagnostic assessments.

Next 2.2 Co-occurring conditions and differential diagnosis